This invention relates in general to door closers and deals more particularly with an improved hydraulic door closer for controlling both opening and closing movements of a door. A door closer of the type with which the present invention is concerned has at least two check valves to provide alternate fluid flow paths between chambers located at opposite sides of a piston. The piston usually has heads at its opposite ends to accommodate the required valves and a closer spring or springs which store energy when an associated door is opened and provide biasing force for returning the door to closed position. The spring or springs act between one of the piston heads and an associated end of the cylinder or housing in which the piston is contained. This arrangement necessitates a relatively long housing to accommodate the combined length of the piston and the closer spring or springs. Heretofore, door closers have been provided which include a piston having a single head at one end and an opening at its opposite to receive a portion of the biasing spring or springs which drive the piston. However, such closers usually have only one check valve and are not capable of back checking, that is checking or cushioning movement of an associated door during at least a portion of its travel toward fully open position.
Accordingly, it is the general aim of the present invention to provide an improved hydraulic door closer for checking movement of a door during at least a portion of its travel in either direction between open and closed positions. It is a further aim of the invention to provide a compact, durable door closer of the aforedescribed general type for low cost manufacture.